Chlamydia continues to be the most commonly reported
nationally notifiable disease, with 1,526,658 cases reported
in 2015 and increasing rates of reported cases over each
of the last two years. Rates of reported chlamydia cases
increased 5.9% during 2014–2015. The Southern region of
the U.S. reported the highest rate of chlamydial infection
in 2015, as well as the largest rate increase during 2014–
2015, at 7.0%. However, the Western region experienced
the largest rate increase in reported chlamydia cases
during 2011–2015, at 10.7%. In 2015, the rate of reported
cases of chlamydia in women was 2.1 times the rate in
men; however, the rate in men increased 20.0% during
2011–2015, whereas, the rate in women increased only
0.3% during the same time frame. After decreasing during
2011–2014, the rate among women aged 15–19 years
increased 1.5% during 2014–2015.
The facilities reporting chlamydial infections have changed
over the last 10 years, with most (78.4%) chlamydia cases
in 2015 reported from venues outside of STD clinics. The
proportion of men being diagnosed with chlamydia in STD
clinics decreased 60.6% from 32.7% in 2006 to 12.9%
STD Surveillance 2015 National Profile: Chlamydia 9
in 2015, and approximately one-third of chlamydia cases
among women were reported from private physicians/
HMOs. Racial differences also persist; reported case rates
and prevalence estimates among Blacks continue to be
substantially higher than among all other racial/ethnic
groups. However, both test positivity and the number of
reported cases of C. trachomatis infections remain high
among most age groups, racial/ethnic groups, geographic
areas, and both sexes